This study aims to estimate the developmental trajectory of grammatical complexity for L2 writers by investigating the extent to which clausal and phrasal complexity is associated with L2 writing proficiency. The corpus used in this study contained 234 argumentative essays of first-year Korean college students at three proficiency levels. The five clausal and four phrasal features were extracted from the tagged corpus to count the frequency of each complexity feature. Our findings demonstrated an association between writing proficiency and clausal and phrasal complexity. Especially noteworthy was that the main source of complexity at each proficiency level (i.e., finite adverbial clauses, WH relative clauses, of phrases as nominal postmodifiers) showed a gradual increase in complexity in terms of two parameters: structural type and syntactic function. A qualitative follow-up analysis provided a detailed description of differences among developmental levels, especially with respect to the lexical associations of particular complexity features. Pedagogical implications are for using empirically derived developmental stages in creating detailed rating scale descriptors and providing more customized writing courses accordingly.

本研究旨在通过调查分句和短语复杂性与二语写作能力的相关程度来估计二语写作者语法复杂性的发展轨迹。本研究使用的语料库包含韩国大学生一年级三个水平的 234 篇议论文。从标记的语料库中提取五个子句和四个短语特征，以计算每个复杂性特征的频率。我们的研究结果证明了写作熟练程度与分句和短语复杂性之间的关联。特别值得注意的是，每个熟练程度的复杂性的主要来源（即有限状语从句、WH关系从句、作为名词性后修饰词的短语）在结构类型和句法功能两个参数方面表现出复杂性的逐渐增加。定性的后续分析提供了发展水平之间差异的详细描述，特别是在特定复杂性特征的词汇关联方面。教学意义在于使用经验得出的发展阶段来创建详细的评分量表描述符，并相应地提供更多定制的写作课程。